(110) cubic and (100) rhombohedral Ge crystal formation on glass using Al-induced crystallization

Begin we have experimentally looked into the physics of low temperature (<400C) amorphous Ge crystallization using AIC favoring the formation of highly oriented large grain Ge crystals towards (110) or (100) suitable for solar cell applications. We have carefully investigated the effects of experimental parameters such as Al and Ge layers thicknesses, interfacial oxide layer (between Al and Ge layers) and annealing conditions on defining the Ge dominant orientation other than normally achieved (111). We have implemented X-Ray diffraction analysis to demonstrate the critical role of oxide layer in reducing the surface free energy. We have studied the playing role of Al thickness on tuning Ge dominant orientation and subsequently achieved (110)-oriented cubic Ge on glass, which could be particularly attractive to mitigate antiphase defect formation during the III-V heteroepitaxy. Furthermore, we show for the first time the possibility of obtaining a novel rhombohedric (100) Ge presenting a remarkable option toward tuning of the Ge lattice constant to ~0.593 nm (instead of 0.565nm ), closely matched to the lattice of InP and related materials.